The invention concerns a method for aligning a dead fish, a head-side section of which is to be separated from its torso at a preset location with a blade of which the cutting edge runs transversely to the orientation of the fish in a cutting plane relative to which the fish is aligned.
Furthermore the invention consists in an apparatus for aligning a dead fish of which a head-side section is to be separated from its torso at a preset location with a blade of which the cutting edge is arranged transversely to the orientation of the fish in a cutting plane relative to which the fish can be arranged to make a blade cut
In the following, the term xe2x80x9cheadxe2x80x9d is to be understood to mean a head-side portion of a fish also possibly including the gills, side fins and/or collar bones. Therefore, fish of which the head as such has already been cut off with such elements left on the torso also have to be considered to fall within the scope of the invention.
Machines for separating a head from a torso of a fish are known. The blade for separating the head is to be guided at a location of the fish at which as much fish flesh as possible remains on the torso, and the head is separated along a rear boundary of its bone facing towards the torso. Here it turned out that side fins mark with sufficient reliability this location which is particularly suitable for separating the head. For this reason the dead fish is aligned with respect to these side fins in a trough which transports the fish and which is divided into head and body supports. A cut is made with a blade along this division, this being either immediately in front of the side fins in a direction towards the head or immediately behind the side fins in a direction towards the torso.
Here it should be taken into account that the dead fish lies in the trough used to convey it with a clearance which allows a movement of the fish in its longitudinal direction. This clearance is smaller for large fish than for small fish. The clearance is limited by means of the side fins which serve as a measure for a cut which separates the head from the torso. These side fins catch when the fish is displaced within the trough in a catching device which is provided for this purpose and in relation to which a cutting plane in which the blade used to separate the head is moved, is positioned.
With known devices for aligning the fish, displacement of the fish within the trough was a problem. This was caused by the fact that the dead fish could not be gripped with the necessary reliability within the trough, so that misalignment were common. In that case for example the fish for the purpose of displacement within the trough was acted upon in the region of its mouth by a slide plate which was intended to displace the fish rearwards in its longitudinal direction in a direction facing away from the head. Depending on the resistance with which the fish met within a trough, the head was deformed without displacement of the fish taking place. The fish therefore could not be moved into a position in which optimum separation of the head from the torso was possible.
Furthermore it has also been attempted to grip the fish in form-locking relationship in the region of its torso in order to align it within the trough. In this case difficulties arose in so far as the torso essentially consists of fish flesh which was deformed elastically when forces were applied by means of a form-locking coupling device, so that in this respect too there was no alignment of the fish, only a random combination of individual influencing variables.
Finally a method for coupling a dead fish to a displacement tool in which the head was coupled to the displacement tool has also already been practiced. The latter had a spike on which the fish head was impaled. The spike extended through the eye sockets of the fish head. This method requires considerable attention and concentration capacity of an operator performing impalement of the head. The operator however over a manageable period of his work with a fish succession of 30 to 40 fishes per minute could not ensure with the necessary reliability that the spike passed through the eye sockets, so that the head was not coupled to a displacement tool with the necessary reliability. Dependence of coupling on the attention of an operator therefore proved to be inadequate.
It is therefore the object of the present invention to couple the fish to an alignment tool so reliably that the head is separated from the torso at a preset location.
This object is now achieved with respect to the method by the fact that the fish is gripped in form-locking relationship at a dimensionally stable location by a movable positioning device and displaced in a direction towards the cutting plane until the preset location lies in the cutting plane.
By coupling the positioning device to a dimensionally stable location of the fish body it is ensured that no inaccuracies in positioning of the fish occur due to elastic deformations of the fish body.
With respect to the apparatus the set object is achieved by the fact that a positioning device which can be brought into form-locking engagement with a dimensionally stable location of the fish and which is provided with a slide mechanism that aligns the fish, is provided.
Due to this positioning device, coupling of the fish becomes independent of the attention of an operator. Coupling to the dimensionally stable location ensures that elastic deformations of the fish body do not lead to unwanted shifting of a cutting point.
According to a preferred embodiment of the invention the preset location is oriented by side fins of the fish. These mark with sufficient reliability the transition from the head to the torso so that, depending on requirements, the head is separated on a side of the side fins facing towards it or on a side of the side fins facing away from it
According to a further preferred embodiment of the invention the positioning device is caught in form-locking relationship in the region of the head. As the head is the only dimensionally stable location of a fish body, it is especially suitable for transmitting the forces applied to the fish body in its region, to the whole of the fish body.
According to a further preferred embodiment of the invention the positioning device penetrates with at least one pointed object into a flesh cover of a skull bone which is present in the course of the lateral boundary surface and in which it is clamped in form-locking relationship. This flesh cover is so thick that the positioning device can be clamped in it. On the other hand the thickness of this flesh cover does not allow deformation with respect to a skull bone covering it. Forces which are applied to the flesh cover are imparted directly to the skull bone and hence to the whole of the fish body.
According to a further preferred embodiment of the invention the positioning unit is guided on an arcuate path which runs roughly in a vertical plane in the lower position of which the pointed object penetrates into the flesh cover of the head. In this way reliable guiding of the positioning device is possible. The latter grips the head at a respectively desired location and holds it fast for a time necessary to make the separating cut. Guiding of the positioning device in a vertical plane can also be achieved structurally very favorably.
According to a further preferred embodiment of the invention the positioning device is conveyed on the path at a speed which corresponds to a speed of conveying the fish. Due to coordination of the two speeds, the fish is guided reliably by the positioning device while it is conveyed and is not released from this guide.
According to a further preferred embodiment of the invention the positioning device is conveyed in the bottom position of the path in the same direction as the fish lying in the trough. In this way the positioning device during conveying does not run in a different direction to the fish lying in the trough. Damage to the fish by different directions of the positioning device on the one hand and of the fish lying in the trough on the other hand is avoided.
According to a further preferred embodiment of the invention the fish gripped by the positioning device is displaced by means of a spring force in the trough until the preset location extends in the cutting plane. This drive for displacement of the fish is simple and hence not susceptible to breakdowns. No operational breakdown during displacement of the fish is to be feared.
According to a further preferred embodiment of the invention the positioning device is provided with at least one pointed object which can be introduced into the fish and which in the region of the head is provided with a mechanism which brings it into form-locking engagement with the fish. This pointed object catches with high reliability in the region of the head with the aid of the mechanism which therefore makes coupling of the fish independent of an operator of the apparatus. In this case according to a further preferred embodiment of the invention the pointed object is provided with two guides, of which a first one extends in the direction of advance maintained by the fish transversely to the longitudinal direction of the fish, and a second one extends transversely thereto in the direction of a longitudinal axis of the fish lying in a conveying device. These two guides allow highly reliable coupling of the fish to the positioning device, so that a decapitating cut can be made at a preset location of the fish body.
According to a further preferred embodiment of the invention the first guide is constructed as an arc which in the region of the head reaches a bottom position adjacent to the head, in which it extends in form-locking relationship into the flesh cover of the head. This guiding along an arc allows reliable catching of the pointed object on the head of the fish. Here, according to a further preferred embodiment of the invention, the guide for the pointed object is in the form of a carousel. The latter according to a further preferred embodiment of the invention consists of a circle curve on which a first suspension of the pointed object is guided, and of a second suspension of the pointed object which is guided relative to the first suspension in such a way that the pointed object is guided over a given distance in its position holding the head. In this way it is possible to carry out the required guiding of the head until the separating cut is made.
According to a further preferred embodiment of the invention, on the circle curve is superimposed an oval channel curve in which the second suspension of the pointed object is guided in such a way that the pointed object in the region of a function zone is oriented vertically and perpendicularly to a trough. The combination of the circle curve with the oval channel curve results, precisely in the region of the necessary function zone, to narrow and precise guiding of the pointed object and hence reliable support of the fish until the head is separated.
According to a further preferred embodiment of the invention the function zone includes lowering of the pointed object in a direction towards the fish lying in the trough, displacement of the fish within the trough until the side fins are caught in a catching device, and lifting of the pointed object out of its form-locking engagement with the fish. These three sections of the function zone determine whether the fish is properly guided during separation of the head and is lying in the correct position in which the head is separated.
According to a further preferred embodiment of the invention the catching device consists of mouldings which on both sides of lateral boundary surfaces are oriented in a direction towards the fish lying in the trough in such a way that the side fins of the fish during displacement thereof are caught in them, so that the fish lies with a preset location in the region of the cutting plane of a decapitating blade. This catching device is also tried and tested with the positioning device according to the invention and leads to optimum performance of the separating cut.
According to a further preferred embodiment of the invention the catching device is divided into at least two sections which are arranged successively in the direction of conveying a trough for catching the fish which after conveying of the fish by a trough width has not yet reached its desired position for separation of the head. Due to this division of the catching device into two or more sections, alignment of the fish in its longitudinal direction is independent in time of the advance of the fish transversely to its longitudinal direction. Instead the alignment can be performed in the longitudinal direction of the fish at a moderate speed of alignment, so that the catching device is thus prevented from not catching the side fins with the necessary reliability. At too high a speed of this longitudinal displacement, it must be expected that the catching device will not grip the side fins with the necessary reliability.
According to a further preferred embodiment of the invention the slide mechanism consists of a spring which moves the pointed object in the direction of the longitudinal axis of the fish in a direction towards the cutting plane. Such spring-dependent operation of the slide mechanism is on the one hand comparatively simple and cheap to execute, but on the other hand operationally very reliable. As a result, very reliable positioning of the fish is achieved with minimum structural expenditure.
According to a further preferred embodiment of the invention the pointed object is biased by a pressure spring which forces it in a direction towards the fish. This pressure spring can be adjusted to the strength conditions on the one hand of the head and on the other hand of the flesh cover, so that on coupling the head there is no need to fear that perhaps the head will be destroyed or coupling will not be effected satisfactorily.
According to a preferred embodiment of the invention a pivot arm which moves the fish is mounted pivotably in a plane in which the fish extends with its longitudinal axis in the trough. This longitudinal axis of the fish is appropriately oriented obliquely to a plane in which the pointed object is brought into form-locking engagement with the head. This oblique orientation has the advantage that the separating cut is made in a plane which runs not at right angles to the longitudinal axis of the fish, but obliquely in order to produce as high as possible a yield of fish flesh which remains joined to the torso of the fish, without considerable quantities of fish flesh remaining on the head on separation of the head.
According to a further preferred embodiment of the invention a stronger spring is provided for large fish and a smaller spring for the displacement of smaller fish. In this way each fish is displaceable within the trough with the force appropriate to it.
According to a further preferred embodiment of the invention the slide mechanism can be locked by a ratchet system in its end position holding the fish in its cutting position. This ratchet system leads to cutting taking place in a fixed position of the fish.
According to a further preferred embodiment of the invention the fish during separation of the head from the torso is biased via the pointed object by the spring. The spring bias which exists for the duration of separation leads to the fact that the fish can be divided at the preset location with the necessary reliability on account of its fixed guiding in the trough.